Fluid‐structure interaction computational analysis of a piston‐cylinder based blast‐wave‐mitigation concept

Ramaswami

Proceedings of the Institution of Mechanical Engineers, Part L:

et al. 2016

The Advanced Combat Helmet (ACH) currently in use is designed for maximum protection against ballistic impacts and hard-surface collisions. It has been well-established now that the ACH provides relatively little protection against blast, and that a significant fraction of the soldiers returning from the recent conflicts suffer from traumatic brain injury (TBI). In the present work, an augmentation of the ACH, which involves the use of a polyurea (a nano-segregated elastomeric copolymer)-based external coating for improved blast protection is considered. To test the utility of this approach, blast experiments are carried out on instrumented head-mannequins. Three configurations of the head-mannequins are investigated: (i) unprotected; (ii) protected using a standard ACH; and (iii) protected using an augmented ACH. To provide additional insight into the problem of blast-wave interaction with a head-mannequin, a series of complementary combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction finite-element analyses is carried out. The results obtained clearly demonstrated that the use of the augmented ACH affects (generally in a beneficial way) head-mannequin dynamic loading and kinematic response as quantified by the intra-cranial pressure, impulse, acceleration, and jolt.

Section: Problem Formulationmentioning

confidence: 99%

RETRACTED: Potential improvement in helmet blast-protection via the use of a polyurea external coating: Combined experimental/computational analyses

Ramaswami

Proceedings of the Institution of Mechanical Engineers, Part L:

et al. 2016

“…A detailed overview of both EOS for the air/detonation-products mixture, and their parameterization for the C-4 high explosive (HE) in the mine, can be found in our prior work. [26][27][28] Since the gaseous mixture has zero effective shear stiffness, shear stresses cannot develop as a result of shear strain, but can develop as a result of a gradient in flow velocity, i.e. shear strain rate.…”

Section: He Chargementioning

confidence: 99%

“…A detailed overview of both EOS for the air/detonation-products mixture, and their parameterization for the C-4 high explosive (HE) in the mine, can be found in our prior work. 26–28…”

Section: Problem Formulation and Computational Analysismentioning

confidence: 99%

Use of aluminum foam core sandwich structures to improve the blast-mitigation performance of light tactical vehicle side-vent-channel solution

Yavari

Proceedings of the Institution of Mechanical Engineers, Part L:

et al. 2016

In our recent work, a side-vent-channel blast-mitigation concept/solution for light tactical vehicles was proposed. As a part of this solution, side-vent channels are attached to the V-shaped vehicle underbody, in order to promote venting of the soil ejecta and gaseous detonation products and, in turn, generate a downward thrust on the targeted light tactical vehicle. As a consequence, the blast loads resulting from a shallow-buried mine detonated underneath a light tactical vehicle are mitigated, improving the probability for vehicle survival. The concept was motivated by the principles of operation of the so-called ''pulse detonation'' rocket engines. To quantify the utility and blast-mitigation capacity of this concept, use was made of several computational and design optimization methods and tools in our prior work. It was found that the capacity of the proposed blast-mitigation solution is relatively small, but still noteworthy. The present work focuses on further improvements in the blast-mitigation capacity of the side-vent-channel solution. Specifically, the benefits offered by substitution of the all-steel side-vent channels with side-vent channels made of sandwich structures (consisting of steel face-sheets and aluminum foam core) for all-steel side-vent channels are explored. The results obtained clearly demonstrated that this substitution can improve the blast-mitigation efficiency of the side-vent-channel solution. In addition, through the use of a design optimization analysis, it was established that this improvement can be further increased through proper grading of the aluminum foam density profile through the sandwich structure core.

“…Equations ( 18) and ( 19), allow determination of U r for a given level of blast intensity. Hence, u p and p r ¼ p g can now be solved using equations ( 8) and (17). Implementation of the procedure described above yields p r ¼ p g ¼ p s and the associated reflection coefficient (p r /p s ) is 1.0 for a rigid structure of infinitesimal mass.…”

Section: Fully Supported Incident Blast Wave Casementioning

confidence: 99%

“…19 Within the third group of strategies, various physical phenomena and processes are utilized in order to lower the strength and increase the thickness of the blast-induced shock wave(s) within the target structure. For example: (i) in the case of polyurea blast wave mitigating coatings, shock wave energy dissipation is accomplished through activation of a secondorder rubbery-to-glassy phase transition under shock loading; 20,21 (ii) in the case of foam-like cellular material-based protective structures, shock energy is dissipated via the cell-wall buckling and cell-wall/cell-wall friction processes; 17 and (iii) in the case of granular material-based protective structures, shock energy is absorbed through a volumetric compaction/densification process. 22 Main objective.…”

Section: Introductionmentioning

confidence: 99%

Computational analysis of fluid–structure interaction based blast-mitigation effects

Proceedings of the Institution of Mechanical Engineers, Part L:

Nataraj

2013

Advanced non-linear dynamics, finite element computational methods and tools are utilized in order to assess the blast wave mitigation potential of the fluid–structure interaction phenomena involving rigid and deformable structures. The employed computational methods and tools are verified and validated by first demonstrating that they can quite accurately reproduce analytical solutions for a couple of well-defined blast wave propagation and interaction problems. Then the methods/tools are used to investigate the fluid–structure interaction phenomena involving deformable structures while accounting for both the interaction of the incident blast wave with the structure and for the structure-motion induced blast wave (at the back-face of the structure). To assess the role of the structure deformability, i.e. the role of the shock waves generated within the structure, the results obtained are compared with their rigid structure counterparts. This comparison established that no additional structure-deformability-related blast-mitigation effects are observed in the case of fully supported blast wave loading while, under exponentially decaying blast wave loading, such effects are observed but only under conditions when the shock wave propagation time within the structure is comparable with the incident wave decay time.